Fibre placement is a method of manufacturing components from composite fibres, such as carbon composite fibre, that involves repeatedly laying down lengths of the composite fibre onto the outer surface of a tool, referred to herein as a placement tool. The outer surface of the placement tool defines the shape and configuration of at least one surface of the component to be formed. The remaining shape and configuration of the composite fibre component is dictated by the subsequent placement of further layers of composite fibre. Common uses of the fibre placement manufacturing method is in the production of composite fibre components within the aerospace industry. For example, this technique is used in the production of long, thin sections of composite fibre such as leading edge spars for helicopter rotor blades or propeller blades. Equally, this technique is also used in the manufacturer of fuselage sections for commercial passenger aircraft.
During this manufacturing process, the fibre placement tools are mounted within a fibre placement machine that as well as being arranged to lay down repeated strips of composite fibre, is also arranged to rotate and otherwise move the fibre placement tool to allow the fibres to be laid down in the desired precise geometry. The current practice for relatively long and thin components, such as rotor blade spars, is to form the fibre placement tool from one or more commonly used engineering metals. The mass of these metallic placement tools can make them difficult to control when being rotated by the fibre placement machine, thus limiting both the length and total mass of the composite fibre component being produced. The existing metallic placement tools can also deflect under the pressure of the fibre placement head of the placement machine and also the rotational forces generated, due to their relative lack of stiffness, thus resulting in the programming of the fibre placement machine having to take this deflection into consideration for the manufacture of the component within the specified dimensions and tolerances. The relative lack of stiffness of the current metallic placement tools also limits the length of single component that can be manufactured using the placement tools, which is an increasing disadvantage as the range and size and composite fibres increases in modern aircraft.
Additionally, the existing metallic placement tools tend to be manufactured as one piece tools. This means that should the design of the corresponding component be changed, for example during the overall design and development phase of the associated structure, a completely new placement tool is required. Similarly, in the event of the placement tool being damaged, which can happen from time to time during the fibre placement process, the entire placement tool must generally be replaced.
It is therefore an object of embodiments of the present invention to provide a fibre placement tool that allows a greater degree of flexibility in the manufacturer of composite fibre components than provided by the existing metallic placement tools.